Lapping arm



March 24, 1942. s, INDGE 2377,04?

LAPPING ARM Filed March 17, 1941 77 swam Patented Mar. 24, 1942 UNITEDSTATES. PATENT OFFICE LAPPING ARM Herbert S. I'ndge, Westboro, Mass.,assignor to Norton Company, Worcester, Mass.,

tion of Massachusetts Application March 17, 1941, Serial No. 383,755

8 Claims.

arm having a yieldably' mounted, reciprocably driven lapping element.Another object of the invention is to provide a lapping arm having workengaging shoes to engage the periphery of the work to be lapped whichserve as a guide for the lapping arm, and to provide the arm with ayieldably mounted reciprocable lapping element.

A further object of the invention is to'provide an improved lapping armconstruction which may be applied as an attachment to a-machine such as,for example, that shown in my prior U. S. Patent No. 2,166,009 datedJuly 11, 1939.

' Other objects will be in part obvious or in part pointed outhereinafter.

.The invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts, as will beexemplified in the structure to be hereinafter described, and

the scope of the application of which will be indicated in the followingclaims.

In the accompanying drawing in which isshown one of various possibleembodiments of the mechanical features of this invention,

Fig. 1 is a fragmentary side elevation of theporting rods or slides land H which serve as supports for a plurality of lapping arm supportingmembers l2. The supporting member I2 is provided with a lower half I3 bymeans of which the supporting member 12 may be readily clamped inadjusted position on the rods l0 and H with a lapping element to behereinafter described in alignment with the work piece to be lapped. Thelapping arm supporting member I2 serves as a support for a pivotallymounted arm I4. A pivotal connection I5 is provided between a corporathesupporting member l2 and the pivotally mounted arm M. A lapping arm I6is pivotally connected by a pivotal connection ll to the upper end ofthe arm II.

The lapping arm l6 comprises a pair of parallel side plates which arespaced apart by spacing blocks I8, I9 and at one end and by a bracket 2|which is formed as an integral extension of a fluid pressure cylinder22.

The lapping arm l6 serves as a support. for a pair of pivotally mountedmembers 23 and 24 which are pivotally connected by studs 25 and 26,respectively, with the lapping arm IS. The arm 23 is provided with apair of work engaging shoes 21 and 28 which are arranged to engage theupper portion of a work piece 29. The lower arm 24 is provided with awork engaging shoe 30 which is arranged to engage the under side of thework piece 29. A pair of toggle levers 3| .and 32 are connected at theiropposite ends by studs 33 and 34, respectively, with the members 23 andThe inner ends of the toggle levers 3| and 32 are connected by a commonstud 35 which slides within elongated slots 36 formed in the oppositeside plates of the lapping arm 16.

A fluid pressure mechanism is provided to actuate the toggle levers 3|and 32 so as to swing the pivotally mounted members 23 and 24 toposition the work shoes 21, 28 and 30 either in an operative position inengagement with the periphery of the work piece 29 (Fig. 1) or in aninoperative position out of engagement with the work after a lappingoperation has been completed. The hydraulic cylinder 22 contains aconnecting rod or link 39, the 'lower end of .which is connected withthe stud 35. In the position of the parts as shown in Fig. 1, fluidunder pressure is admitted from a source of supply, such as a fluid pump(not shown) within the base of the crankshaft lapping machine, through40 and a passage 4|, into a cylinder the pipe chamber 42-, to cause thepiston 36 to move upwardly toward the right to the position-shown inFig. 1'. During this movement fluid is exhausted from a cylinder chamber43 above the piston 36 through a pipe 44 into a reservoir (not shown).

After a lapping operation has been completed and it is desired to removethe work engaging 7 shoes 21, 28,and 30 from operative engagement withthe work piece 29, the direction of movement. of fluid under pressure isreversed and fluid under pressure is passed through the pipe 24,respectively' it into the cylinder chamber 33 to cause a downwardmovement of the piston 36 which transmits a downward movement toward theleft through. the piston rod 31, connecting; rod or link 39, to move thestud 35 downwardly within the elongated slots 36, which movement servesto break;

'the toggle levers 3| and 32 so as to rock the arms --arm supportingmember i2 to serve as a guide for the'lapping arm i5 during its swingingmovement.

In order to attain one object of the invention, the lapping arm I6 isprovided with a reciprocable lapping element comprising a lapping stick"59 of bonded abrasive material which is arranged to be reciprocated ata comparatively rapid rate while maintained in yielding engagement withthe periphery of the work piece to be lapped.

The swinging arm 23 is pro ided with an upwardly extending portion 55which is provided with a plurality of elongated slots 52, 53, 54 and 55which serve to support a pair of spaced parallel yieldable elements,such as relatively thin fiat springs 56 and 51. The thickness of thesprings 56 and 51 has been somewhat exaggerated in the drawing in orderto clarify the illustration. A pair of plates 58 and 59 are providedadjacent to the upper ends of the springs 56 and 51. A plurality ofstuds 60, 6|, 62 and 63 loosely fit within the elongated slots 52, 53,54 and 55, respectively. The studs 68, 6|, 62 and 63 are provided withthreaded end portions 64 and 65. The threaded portions 64 and 65 of thestuds pass through holes formed in the springs 56 and 51, respectively,and pass through corresponding holes in the plates 58 and 59. Clampingnuts 66 and 61 are provided to clamp the plates 58 and 59. and thesprings 56 and 51, respectively, into fixed relation with the studs 60,6|, 62 and 63. The length bf the body of the studs 60, 6|, 62 and 63 isslightly greater than the thickness of the member 5| so that due to theelongated slots 52, 53, 54 and 55, the springs 56 and 51 are free toslide'in a substantially vertical direction. The lowerend of. thesprings 56 and 51 are fastened to a block 66 by means of screws 69 and19. The block 68 serves as a support for a lapping stick holder 1| whichsupports the lapping stick 50.

The fiat supporting springs 56 and 51 are relatively thin so that thelapping stick 58 may be reciprocated in operative contact with theperipheral surface of the crankpin 29 to be ground. A crank motion isprovided for oscillating or reciprocating the stick 50 which maycomprise a rock shaft journalled within the arm 23. The rock shaft 15supports a downwardly extending arm 16 having a rounded and 11 whichengages a hole 18 formed in the block 68 (Fig. 3). A rock arm 19 ismounted on the other end of the rock shaft 15. The upper end of the arm19 is provided with a vertically extending groove 80 within whichacrankpin 8| rides. The crankpin 8| is eccentrically mounted on arotatable plate 82 formed on the lower end of a rotatable shaft 83. Theupper end of the shaft 83'carries a gear 84 which meshes with'a gear 85.The

gear 85 is mounted on a rotatable shaft 86. It will be readily apparentfrom the foregoing disclosure that rotation of the shaft 86 will betransmitted through the gear 85, the gear 84, the shaft 83, to revolvethe crankpin 8| (Fig. 3) which in turn will oscillate the rock arm 19,the rock shaft 15, and the rock arm 16 to oscillate or reciprocate thelapping stick 50 so that it abrades or laps the entire length of theperipheral surface of the crankpin 29 as it is rotated.

It is desirable that the lapping stick 50 be maintained in yieldingengagement with the work piece 29 so that a uniform engagement of thelapping stick 56 may be had during its entire reciprocatory stroke. Inorder to accomplish this desired result, a pair .of compression springs81 and 88 are interposed between the member 5| and the block 68. Due tothe fact that the springs 56 and 51 together with the entire lap elementassembly are free to move in a vertical direction, the compressionsprings 81 and 88 will maintain the lapping stick 50- in yieldingengagement with the periphery of the crnakpin 29 during the lappingoperation.

A suitable driving mechanism is provided whereby a plurality of lappingarms may be utilized and a plurality of lapping sticks- 50 supportedthereby may be readily driven. A pair of spaced brackets 95, only one ofwhich has been shown in the drawing, serve as a support for a rotatableshaft 9| which is driven by means of an electric motor 92. Each of thelapping arm supporting members I2 is provided with an upwardly extendingbracket 93 each of which contains a spiral gear 94 which is slidablykeyed to the shaft 9| so as to facilitate a longitudinal adjustment ofthe lapping arm supporting member |2 in setting up the machine. Each ofthe spiral gears 94 meshes with a spiral gear 95 which is rotatablysupported within the bracket 93 and is drivingly connected by means of aflexible driving shaft 96 with the shaft 86 on the lapping arm l6. Itwill be readily apparent from the foregoing disclosure that rotation ofthe shaft 9| by the motor 92 will be transmitted through the spiral gear94, the spiral gear 95, the flexible driving shaft 96, to rotate theshaft 86 and thus transmit a reciprocatory movement to the lapping stick50. Due to the flexible driving shaft 96, the lapping arm l6 may readilyswing in a desired path as the crankpin 29 revolves during a lappingoperation.

It will be readily apparent from the foregoing disclosure that one ormore of the improved lapping arms l6 may be mounted on a crankshaftlapping machine of the type shown in my prior U. S. Patent No.2,166,009. The driving mechanism including the shaft 9| and electricmotor 94 together with thespaced supporting brackets may be readilysupported on the pivotally mounted lap supporting arms 80 so that theentire lapping arm assembly may be readily rocked to an inoperativeposition during the loading operation.

The operation of the improved lapping arm will be readily apparent fromthe foregoing disclosure. Assuming the parts to have been previouslyadjusted, when it is desired to start a lapping operation fluid underpressure is admitted through the pipe 48, to the cylinder chamber 42, tomove the piston 36 into the position illustrated in Fig. 1, whichmovement shifts the toggle levers 3| and 32 into the straight lineposition to swing the work engaging shoes 21, 29

and 30 into operative engagement with the work piece 29. At the sametime, the electric motor 92 is started which, in a manner hereinabovedescribed, serves through the flexible driving shaft 96 to impart arapid reciprocatory movement to one or more of the lapping sticks 50,depending upon the number of lapping arms l6 mounted upon the machine.

It will thus be seen that there has been provided by this inventionapparatus in which the various objects hereinabove set forth togetherwith many thoroughly practical advantages are successfully achieved. Asmany possible embodiments may be made of the above invention and as manychanges might be made in the embodiment above set forth, it is to beunderstood that all matter hereinbefore set forth or shown in theaccompanying drawing is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. In a lapping machine having a movable lapping arm, a work engagingshoe on said arm to engage the periphery of a work piece so as to takeup the thrust of said arm, a reciprocable lapping stick on said armadjacent to said shoe, a fiat spring on said arm which is free to movein a direction normal to the work axis to support said lapping stick,and means to flex said spring so as to impart a reciprocatory movementto said lapping stick.

2. In a lapping machine having a pivotally mounted lapping arm, a workengaging shoe on said arm'to engage the periphery of a work piece so asto support and steady one end of said arm,

a reciprocable lapping stick on said arm adjacent to said shoe, a fiatspring on said arm which isarranged to move in a direction normal to thework axis to support said lapping stick, yieldable means to maintainsaid lapping stick in yielding engagement with a work piece, and meansto flex said spring so as to impart a reciprocatory movement to saidlapping stick.

3. In a crank lapping machine having a pivotally mounted lapping arm, apair of toggle levers mounted on said arm, means to actuate said togglelevers, opposed work engaging shoes each one connected to one of saidlevers, a reciprocable lapping stick, a fiat spring connected with oneof said levers yieldably to support said lapping stick in operativeengagement with the periphery of a work piece, and means including anoscillatable lever to flex said spring so as to impart a reciprocatorymovement to said lapping stick.

4. In a crank lapping machine having a pivotally mounted lapping arm, apair of toggle levers mounted on said arm, means to actuate said togglelevers, opposed work engaging shoes each connected to one of saidlevers, a reciprocable lapping stick, a pair of spaced fiat parallelsprings connected with one of said levers yieldably to support saidlapping stick in operative engagement with the periphery-of a workpiece,

and means including an oscillatable lever to'flexsaid spring so as toimpart a reciprocatory movement to'said lapping stick.

5. In a crank lapping machine having a piv- 65 otally mounted lappingarm, a pair of toggle levers mounted on said arm, means to actuate saidtoggle levers, opposed work steadying shoes each connected to one ofsaid levers so as to take up the thrust of said arm, a reciprocablelapping 6 stick, a fiat spring on one of said levers which is free tomove in a direction normal 'to thework axis to support said lappingstick, yieldable means to maintain said lapping stick in yieldingengagement with a work piece, and means in- 10 eluding a positivelyrotated crank operatively connected to flex said spring so as to imparta reciprocatory movement to said lapping stick.

' port for a rotatable work piece, a pivotally mounted lapping arm, apair of toggle levers mounted on said arm, means to actuate said togglelevers, opposed work steadying shoes,.each shoe connected to one of saidlevers so as to support and steady one end of said arm relative to thework piece, a reciprocable lapping stick, a pair of flat parallel spacedsprings. on one of said levers which are free to move in a directionnormal to the work axis to support said lapping stick, yieldable meansto maintain said lapping stick in yielding engagement with a workpiece,and means including a positively rotated crank operatively connected toflex said springs so as to impart a reciprocatory movement to saidlapping stick. 2

'7. In a crank lapping machine having a support for a. rotatable workpiece, a pivotally mounted lapping arm, a pair of toggle levers mountedon said arm, means to actuate said toggle levers, opposed work engagingshoes each connected to one of said levers so as to support and steadyone end of said arm relative to the work piece, a reciprocable lappingstick, a pair of flat parallel spaced springs on one of said leverswhich are free to move in a direction normal to the work axis to supportsaid lapping stick,

means including a crankpin operatively connected to flex said springs soas to impart a reciprocatory movement to said lapping stick, and aflexible driving shaft operatively connected to rotate said crankpin,whereby a reciprocatory motion may be transmitted to the lapping stickduring the swinging movement of the lapping arm.

8. In a crank lapping machine having a pivotally mounted lapping arm, apair of toggle levers mounted on said arm, means to actuate said togglelevers, opposed work engaging shoes each connected to one of saidlevers, a reciprocable lapping stick, a pair of flat parallel spacedsprings which are free to move in a direction normal to the work axis tosupport said lapping stick, means including a crankpinoperativelyconnected to fiex'said springs, a motor driven shaft on said machine,and a flexible driving 0 shaft operatively connected between said motordriven shaft and said crankpin whereby rotation of said shaft serves torevolve said crankpin so as to fiex'said springs and thereby impart areciprocatory motion to the lapping stick.

, HERBERT S. INDGE.'

